Effects of artificial dawn and morning blue light on daytime cognitive performance, well-being, cortisol and melatonin levels
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Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and mood. Here we investigated the role of morning light exposure as a countermeasure for impaired cognitive performance and mood under sleep restriction (SR). Seventeen participants took part of a 48h laboratory protocol, during which three different light settings (separated by 2 wks) were administered each morning after two 6-h sleep restriction nights: a blue monochromatic LED (light-emitting diode) light condition (BL; 100 lux at 470 nm for 20 min) starting 2 h after scheduled wake-up time, a dawn-simulating light (DsL) starting 30 min before and ending 20 min after scheduled wake-up time (polychromatic light gradually increasing from 0 to 250 lux), and a dim light (DL) condition for 2 h beginning upon scheduled wake time (<8 lux). Cognitive tasks were performed every 2 h during scheduled wakefulness, and questionnaires were administered hourly to assess subjective sleepiness, mood, and well-being. Salivary melatonin and cortisol were collected throughout scheduled wakefulness in regular intervals, and the effects on melatonin were measured after only one light pulse. Following the first SR, analysis of the time course of cognitive performance during scheduled wakefulness indicated a decrease following DL, whereas it remained stable following BL and significantly improved after DsL. Cognitive performance levels during the second day after SR were not significantly affected by the different light conditions. However, after both SR nights, mood and well-being were significantly enhanced after exposure to morning DsL compared with DL and BL. Melatonin onset occurred earlier after morning BL exposure, than after morning DsL and DL, whereas salivary cortisol levels were higher at wake-up time after DsL compared with BL and DL. Our data indicate that exposure to an artificial morning dawn simulation light improves subjective well-being, mood, and cognitive performance, as compared with DL and BL, with minimal impact on circadian phase. Thus, DsL may provide an effective strategy for enhancing cognitive performance, well-being, and mood under mild sleep restriction.
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Most of the effects of gradually increasing light were visible on the first day after the sleep restriction night but not on the second day after two nights of sleep restriction.
“Most of the effects were visible on the first day after the sleep restriction night but not on the second day after two nights of sleep restriction, most likely due to the increase in sleep pressure.”
From Dawn simulation light impacts on different cognitive domains under sleep restriction (2015) · cites this paper as [14]
The Discussion says dawn-simulation light improved cognitive performance after the first sleep-restriction night but that this benefit was not maintained after the second; it proposes increased sleep pressure as a possible explanation. The claim overgeneralizes this pattern: the Subjective Assessment section reports benefits for well-being and tension after the second night. Page numbers are unavailable in our copy. (LLM, conf=0.87)
Experimental — accuracy not yet measuredExposure to gradually increasing light prior to awakening can counteract sleep restriction effects on well-being and cognitive performance across the day, leading to an optimized level of alertness and enhanced performance on specific cognitive tasks tightly related to sustained levels of attention.
“In a previous study, we have shown that exposure to gradually increasing light prior to awakening can counteract sleep restriction effects on well-being and cognitive performance across the day, leading to an optimized level of alertness, which impinges on enhanced performance on specific cognitive tasks tightly related to sustained levels of attention [14].”
From Dawn simulation light impacts on different cognitive domains under sleep restriction (2015) · cites this paper as [14]
Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.
Experimental — accuracy not yet measuredMorning light exposure (dawn simulation light) increased wellbeing and enhanced performances across the day.
“and from our previous analysis in which morning light exposure (dawn simulation light) increased wellbeing and enhanced performances across the day [14].”
From Dawn simulation light impacts on different cognitive domains under sleep restriction (2015) · cites this paper as [14]
Artificial morning dawn simulation light improves subjective perception of well-being and mood, as well as cognitive performance across the day under conditions of mild sleep restriction.
“Our results corroborate our previous analysis that artificial morning dawn simulation light improves subjective perception of well-being and mood, as well as cognitive performance across the day under conditions of mild sleep restriction [14].”
From Dawn simulation light impacts on different cognitive domains under sleep restriction (2015) · cites this paper as [14]
Other scientific research supports the benefits of applying blue light to improve sleep quality.
“Although devices such as the Withings Aura and REM Sleep Tracker, Re-Timer and AYO have not been independently validated, other scientific research supports the benefits of applying blue light to improve sleep quality (Viola et al., 2008; Gabel et al., 2013; Geerdink et al., 2016).”
From A Critical Review of Consumer Wearables, Mobile Applications, and Equipment for Providing Biofeedback, Monitoring Stress, and Sleep in Physically Active Populations (2018) · cites this paper as Gabel et al., 2013
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- Authors
- Gabel, V., Maire, M., Reichert, C. F., Chellappa, S. L., Schmidt, C., Hommes, V., Viola, A. U., & Cajochen, C.
- Affiliations
- University of Basel (CH)
- Corresponding author
- Viola, Antoine U.
- ORCID
- Venue
- Chronobiology International
- Publisher
- Informa UK Limited
- Published
- 2013-07-10
- Volume
- 30
- Issue
- 8
- Pages
- 988-997
- ISSN
- 0742-0528 (ISSN-L)
- 1525-6073
- OpenAlex
- W2140601229
- Cited by
- 154
- References
- 58
- Citations by year
- 2026: 10 · 2025: 10 · 2024: 16 · 2023: 17 · 2022: 13 · 2021: 12 · 2020: 11 · 2019: 12 · 2018: 12 · 2017: 13 · 2016: 6 · 2015: 16 · 2014: 4 · 2013: 2
- FWCI
- 12.62
- Type
- journal article
- Language
- en
- Open access
- green
- orbi.uliege.be
- Licence
- other-oa
- Locations
- Chronobiology International (publishedVersion)
- PubMed (publishedVersion)
- ORBi (University of Liège) (submittedVersion, other-oa)
- ePrints Soton (University of Southampton) (submittedVersion)
- Topics
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
- Keywords
- sleep restriction, cognitive performance, mood, well-being, salivary cortisol, melatonin, circadian phase, subjective sleepiness
- MeSH terms
- Adult, Affect, Analysis of Variance, Circadian Rhythm, Cognition, Europe, Health Status, Humans, Hydrocortisone, Male, Melatonin, Phototherapy, Saliva, Seasons, Sleep, Time Factors, Wakefulness, Biomarkers, Treatment Outcome, Photoperiod, Dyssomnias, Young Adult
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